120 lines
2.5 KiB
Go
120 lines
2.5 KiB
Go
package object
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import (
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"sort"
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"zworld/engine/util"
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)
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type Query[K Component] struct {
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results []K
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filters []func(b K) bool
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sorter func(a, b K) bool
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}
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// NewQuery returns a new query for the given component type
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func NewQuery[K Component]() *Query[K] {
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return &Query[K]{
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filters: make([]func(K) bool, 0, 8),
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results: make([]K, 0, 128),
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}
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}
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// Where applies a filter predicate to the results
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func (q *Query[K]) Where(predicate func(K) bool) *Query[K] {
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q.filters = append(q.filters, predicate)
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return q
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}
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// Sort the result using a compare function.
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// The compare function should return true if a is "less than" b
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func (q *Query[K]) Sort(sorter func(a, b K) bool) *Query[K] {
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q.sorter = sorter
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return q
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}
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// Match returns true if the passed component matches the query
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func (q *Query[K]) match(component K) bool {
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for _, filter := range q.filters {
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if !filter(component) {
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return false
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}
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}
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return true
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}
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// Append a component to the query results.
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func (q *Query[K]) append(result K) {
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q.results = append(q.results, result)
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}
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// Clear the query results, without freeing the memory.
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func (q *Query[K]) Reset() *Query[K] {
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// clear slice, but keep the memory
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q.results = q.results[:0]
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q.filters = q.filters[:0]
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return q
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}
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// First returns the first match in a depth-first fashion
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func (q *Query[K]) First(root Component) (K, bool) {
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result, hit := q.first(root)
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return result, hit
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}
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func (q *Query[K]) first(root Component) (K, bool) {
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var empty K
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if !root.Enabled() {
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return empty, false
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}
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if k, ok := root.(K); ok {
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if q.match(k) {
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return k, true
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}
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}
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if group, ok := root.(Object); ok {
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for _, child := range group.Children() {
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if match, found := q.first(child); found {
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return match, true
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}
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}
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}
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return empty, false
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}
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// Collect returns all matching components
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func (q *Query[K]) Collect(roots ...Component) []K {
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// collect all matches
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for _, root := range roots {
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q.collect(root)
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}
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// sort if required
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if q.sorter != nil {
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sort.Slice(q.results, func(i, j int) bool {
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return q.sorter(q.results[i], q.results[j])
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})
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}
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return q.results
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}
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func (q *Query[K]) CollectObjects(roots ...Component) []Component {
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return util.Map(NewQuery[K]().Collect(roots...), func(s K) Component { return s })
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}
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func (q *Query[K]) collect(object Component) {
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if !object.Enabled() {
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return
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}
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if k, ok := object.(K); ok {
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if q.match(k) {
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q.append(k)
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}
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}
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if group, ok := object.(Object); ok {
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for _, child := range group.Children() {
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q.collect(child)
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}
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}
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}
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